1. Field of the Invention
This invention relates to a photographic camera designed on the basis of energy saving consciousness. More in particular, this invention relates to an automatic camera in which a solar battery is used to supply power at least partly.
2. Description of the Prior Art
It is a current trend to use a photovoltaic element such as a solar battery comprised of an array of solar cells as a power source of an automatic camera, and several proposals have been made to incorporate such a solar battery into a camera. However, it is generally understood that use of a solar battery alone to meet all the power requirements of an automatic camera cannot be made without difficulty. For example, a considerably large amount of current is required to operate the shutter of a camera, and, therefore, a considerably large area must be reserved on the surface of a camera for solar cells if such a large current is to be supplied by a solar battary alone. Since the surface of a camera body is rather limited, only an insufficient area is available for a solar battery, which, in turn, requires to provide another power source. Accordingly, it has been common practice to use a secondary battery as well as a solar battery, thereby it is so structured that the secondary battery is charged by the solar battery and a required power is supplied to the control circuit of a camera from the secondary battery.
It is true that a secondary battery may be put in use for a longer period of time by recharging; however, the secondary battery also needs to be replaced once in a while from various reasons such as deterioration in performance due to aging and malfunctioning. Besides, what is rather problematical is that replacement of secondary batteries for use in a camera is not at user's disposal because they are simply not available in the market. Camera batteries which are available in the market are primary batteries which are not reversible, and, therefore, they cannot be recharged for a repetitive use. If an attempt is made to recharge a primary battery, gas will be produced inside the battery, resulting in an explosion in an extreme case.
It is also to be noted that the provision of a solar battery should not cause any inconveniences. For example, the upper cover of a camera body will be the most appropriate place to provide a solar battery. However, there are many moving and adjusting parts such as a film winding lever on top of the upper cover, a solar battery, when mounted, should not constitute an obstruction for the operator. Moreover, it is quite important that a solar battery be well protected, especially against external forces. Because, a solar battery is a kind of the components which are mounted to be of service for the life of a camera, and, therefore, replacement of solar batteries cannot usually be made without considerable difficulties.